This invention relates to conveyor belt structures for conveying materials into a heated oven, and more particularly relates to a novel construction for securing a guide V-belt to an open-mesh fabric belt of high temperature-resistant material.
The guiding of endless conveyor belts is a well known art. Such conveyor belts when of substantially non-extensible material, such as rubber or cotton, may be guided for high speed movement through the use of crowned rollers and through the use of suitable adjustable rollers. Cotton and rubber belts have also been successfully guided without the use of crowned rollers or adjustable rollers by securing a V-cross section belt to their underside and permitting this V-belt to run in a grooved roller of pulley to guide the entire belt against lateral drift. The V-belts are easily secured to solid rubber or cotton belts by a vulcanization process.
Conveyor belts are required to convey printed or coated graphic arts material from the printing apparatus into curing or drying ovens. These belts are preferably belts using an open-mesh fabric so that they can move over a vacuum bed which will assist in holding printed or coated sheets on the belt. Further, the open-mesh fabric belt material must be one which is resistant to the relatively high temperatures of the curing or drying oven. In view of the open-mesh construction of these belts, they are generally extensible and have no lateral stability since they will easily flex (or wrinkle) in the plane of the web. Open-mesh or net-type materials which have been used for this purpose have used fiber glass filaments woven into an open-mesh form. These filaments have also been made of plastics including a plastic known by the trademark Kevlar made by duPont. Other similar materials which are coated with Teflon have been used. It has been found that these materials will not permit chemical bonding to the conventional V-belt used for guiding conveyor belts of prior art and, as a result, guiding has been attempted through the use of crowned rollers and adjustable rollers and the like. However, the extensibility of the open mesh web requires frequent manual tension adjustments, particularly when oven temperatures are changed or when conveyor belt speed is changed.